Forty-five years ago, as the Vietnam war raged on, Army Spc. Hagel and Nguyen Tan Dung were on opposite sides of combat serving in the Mekong Delta both wounded more than once as they battled for their countries.
This weekend the two men, now America's defence secretary and Vietnam's prime minister, met at the start of an international security conference here, working to help build America's growing military partnership with Vietnam.
While Hagel and Dung knew of each other's service in Vietnam, they had never met. So this meeting gave them the chance to exchange war stories.